secretary of energy stephen chu announced today he's stepping down. during his tenure, he came under fire for the handling of a solar energy loan to solyndra. it later went bankrupt and laid off all its workers. chu will stay on at least until the end of february, or until president obama names his successor. nasa paused today to remember the lives of seven astronauts who died ten years ago when space shuttle "columbia" broke apart in the air over texas. a few hundred people gathered at kennedy space center in florida including family members and other astronauts. the accident happened as the shuttle was returning home with only 16 minutes left till landing. the brash, bold-talking former mayor of new york city, ed koch died today of congestive heart failure at a hospital in new york. >> good morning. i'm ed koch, and i'm running for mayor. how am i doing? >> sreenivasan: ed koch was most at home on the streets of manhattan. a quintessential new yorker, the larger than life koch, who ran city hall from 1978 to 1989, was best known for shepherding new